"The watch can and should, for most of us, eliminate passcodes altogether on iPhones, and Macs and, if Apple's smart, PCs: As long as my watch is in range, let me in!"

Obviously, some security concerns come to mind.

In order to make it totally secure, Tognazzini writes, Apple would first need to implement a security feature where if you remove the watch, you would need to somehow reestablish authenticity when you put it back on.

Another extra security precaution could be something like two-factor authentication. For example, people with the iWatch who want further security could require both the presence of the watch and a passcode.